Zinc supplementation might potentiate the effect of vitamin A in restoring night vision in pregnant Nepalese women.

Abstract

BACKGROUND:

Zinc deficiency may result in abnormal dark adaptation or night blindness, a symptom primarily of vitamin A deficiency. During a placebo-controlled trial in Nepal, weekly vitamin A supplementation of women reduced but failed to eliminate the incidence of night blindness during pregnancy, suggesting a role for zinc.

OBJECTIVE:

The study examined the efficacy of daily zinc supplementation in restoring night vision of pregnant women who developed night blindness while routinely receiving either vitamin A, beta-carotene, or placebo in a field trial.

DESIGN:

Women (n = 202) who reported to be night blind during pregnancy were randomly assigned in a double-blind manner, stratified on vitamin A, beta-carotene, or placebo receipt, to receive 25 mg Zn or placebo daily for 3 wk. Thus, the 6 groups studied were as follows: beta-carotene + zinc, beta-carotene alone, vitamin A + zinc, vitamin A alone (vitamin A + placebo), zinc alone (zinc + placebo), and placebo (2 placebos: one for the vitamin A or beta-carotene study and one for the zinc study). Women underwent a clinic-based assessment that included pupillary threshold testing and phlebotomy before and after supplementation. Supplement use and daily history of night blindness were obtained at home twice every week.

RESULTS:

Zinc treatment increased serum zinc concentrations, but alone (zinc alone group), failed to restore night vision or to improve dark adaptation. However, women in the vitamin A + zinc group who had baseline serum zinc concentrations <9.9 micromol/L were 4 times more likely to have their night vision restored (95% CI: 1.1, 17.3) than were women in the placebo group and tended to have a small improvement in pupillary threshold scores (by 0.21 log candela/m2; P = 0.09).

CONCLUSION:

These data suggest that zinc potentiated the effect of vitamin A in restoring night vision among night-blind pregnant women with low initial serum zinc concentrations.

• Authors: P Christian, S K Khatry, S Yamini, R Stallings, S C LeClerq, S R Shrestha, E K Pradhan, K P West Jr
• Journal: The American journal of clinical nutrition (Am J Clin Nutr) Vol. 73 Issue 6 Pg. 1045-51 (Jun 2001) ISSN: 0002-9165 [Print] United States
• PMID: 11382658 (Publication Type: Clinical Trial, Journal Article, Randomized Controlled Trial, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• beta Carotene
• Vitamin A
• Zinc

Topics

• Adult
• Double-Blind Method
• Drug Synergism
• Female
• Humans
• Nepal
• Night Blindness (drug therapy)
• Pregnancy
• Pregnancy Complications (drug therapy)
• Reflex, Pupillary (drug effects)
• Regression Analysis
• Treatment Outcome
• Vitamin A (therapeutic use)
• Vitamin A Deficiency (complications)
• Zinc (blood, deficiency, therapeutic use)
• beta Carotene (administration & dosage, therapeutic use)